udf: Limit sparing table size

Although UDF standard allows it, we don't support sparing table larger
than a single block. Check it during mount so that we don't try to
access memory beyond end of buffer.

Reported-by: syzbot+9991561e714f597095da@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/super.c

@@ -1345,6 +1345,12 @@ static int udf_load_sparable_map(struct super_block *sb,
 			(int)spm->numSparingTables);
 		return -EIO;
 	}
+	if (le32_to_cpu(spm->sizeSparingTable) > sb->s_blocksize) {
+		udf_err(sb, "error loading logical volume descriptor: "
+			"Too big sparing table size (%u)\n",
+			le32_to_cpu(spm->sizeSparingTable));
+		return -EIO;
+	}
 
 	for (i = 0; i < spm->numSparingTables; i++) {
 		loc = le32_to_cpu(spm->locSparingTable[i]);